Special Report: Health Impacts of Shale Gas Boom Still Unproven

by John Gever John Gever Senior Editor, MedPage Today
December 04, 2011

Across northern Appalachia, many rural communities that have been slowly dying since the 1920s are enjoying -- if that's the right word -- a sudden rush of prosperity thanks to the boom in drilling for natural gas in the so-called Marcellus Shale formation.

Marcellus Shale is a thick bed of rock about a mile beneath the surface of a region extending from central New York state into portions of Tennessee and Virginia, and as far west as Ohio. Geologists have long known that the formation harbored large deposits of natural gas, but only recently has drilling technology been able to extract the gas economically.

In the past five years, thousands of new wells have been drilled in the region, bringing an influx of workers and money that many towns had not seen in decades.

But although the region was the original home of oil and gas production -- Col. Edwin Drake drilled the nation's first oil well in northwestern Pennsylvania in 1858 -- the new bonanza came as a surprise and even a shock to many in the area.

Residents have worried that the drilling is putting their health at risk by exposing them to toxic chemicals, air pollution, and noise. Some have gone beyond worrying, charging that they or people they know who live near drilling sites have been sickened by polluted well water or airborne exposures.

Last month, the University of Pittsburgh's Graduate School of Public Health sponsored a conference on the health impacts from Marcellus Shale gas extraction, with speakers from a range of disciplines.

The take-away messages from the conference:

A few people have had clearly documented health problems related to the Marcellus gas boom, but these were occupational exposures in rig workers.

Some aspects of gas drilling and production release toxins into the environment, but the level of exposure to the public is uncertain and no links to specific instances of disease have been confirmed, and may never be.

The most likely impacts are not those typically highlighted in media coverage.

A Primer on Gas Drilling Technology

In order to understand why shale gas drilling might affect public health, it's necessary to know something about the technology.

Two recent developments made Marcellus Shale gas economically attractive. Another vital element is as old as a French-born, English-reared inventor by the name of Rudolf Diesel.

One of the new developments is hydraulic fracturing, or "fracking," in which vast quantities of water laced with other chemicals are injected into the shale under high pressure. The point is to create a web of fissures in the rock through which the gas can escape.

Before getting to that point, though, the well has to be drilled. For a well to produce enough gas to be worth the expense of drilling a mile down, it can't just prick the gas bed at a single point, as traditional equipment does, but must tunnel along through the rock horizontally for hundreds of feet.

Enter the second bit of new technology: drilling apparatus that can make turns, making horizontal wells possible.

The old technology relevant to the health discussion is the diesel engine, which powers most of the machinery needed to drill wells and move the gas above ground.

The drill rigs themselves are usually diesel-powered, but more important, so is the vast fleet of earthmovers and trucks needed to create and service the drill site. Diesel engines also drive the compressors and pumps that push the gas through the distribution pipelines.

Once the well is drilled and fracked -- a process that takes about three to four weeks -- some of the fracking fluid, known as backflow, comes up out of the well. It is stored temporarily in above-ground ponds, then trucked away for treatment (often in municipal sewage plants) and discharge into rivers, or for reuse in other fracking operations.

And for a time after the gas starts up from the well, when it is too dirty to be sent into the pipeline system, it is often vented directly into the air or, more commonly, flared -- pumped through a tall stack and burned, with the flames shooting far into the air.

Some numbers provided at the Pittsburgh conference by Carl Werntz, DO, MPH, an occupational health specialist at West Virginia University in Morgantown, and derived from industry publications, hint at the scale of these activities.

A single fracked well requires an average of about 5.7 million gallons of fluid, of which 99.5% is water. The remaining 0.5% -- about 28,000 gallons -- is a complex and proprietary mix of surfactants, corrosion and scale inhibitors, lubricants, biocides, and other chemicals. Hydrochloric acid appears to be a common and relatively high-volume component.

And then there's the diesel fuel, and it attendant emissions. More on that later.

Did Fracking Cause My Son's Cancer (or Autism)?

Werntz said the known fracking additives include a range of compounds with well-known effects on the skin or respiratory system with direct exposure. But outside the occupational setting, such exposures are virtually unknown.

The most likely routes would be underground leakage from well casings or escapes from the backflow ponds into groundwater or surface streams, to which a well site's neighbors might be exposed.

But in that scenario the fracking chemicals would presumably be highly diluted. Rob Jackson, PhD, of Duke University, said preliminary results from a study he and his colleagues conducted in northeastern Pennsylvania showed no evidence of fracking fluids or brine in well water sampled from more than 200 sites.

Jackson said the study did identify higher concentrations of methane in drinking water in sites near drilling activities compared with control sites. But the concentrations were below levels known to be toxic, and he stressed that there was no baseline data from before Marcellus Shale gas operations began -- a common theme in nearly all the research conducted so far.

Few rural homeowners have had their well water tested in a scientifically acceptable way, so it may never be known what, if anything, gas drilling might have added to it. Jackson showed a picture of a plastic jug filled with a murky liquid, saying it was typical of what homeowners want tested.

Bernard Goldstein, MD, former dean of public health at Pitt, reminded attendees at the conference that, because gas drilling is so common in the region, it is certain that disease clusters will occur in places where drilling has occurred -- "whether causally related or not."

The immediate past president of the Pennsylvania Medical Society, Ralph Schmeltz, MD, attended the conference and told MedPage Today that this was a problem for physicians right now.

"We're stuck in a position where patients may come to us about a symptom, and we can't tell them definitively how that symptom may relate to drilling or anything in their area," he said.

However, that hasn't been the case for about a dozen patients who went to the occupational health clinic in Morgantown where Werntz practices.

"The Sparkly Cloud"

Werntz said he has seen perhaps six or eight workers with chemical burns and/or breathing problems caused by fracking chemicals that spilled on their hands or clothing.

In the early days of Marcellus Shale drilling, he explained, the drill rigs had come from Texas, Oklahoma, and Wyoming where gas exploration has been going on for decades -- and where the roads are a lot wider and straighter than in West Virginia and western Pennsylvania. Often it was necessary to park the chemical trucks at the bottom of a tortuous access road, then haul the fracking chemicals up to the site by hand in buckets.

Another five workers, more seriously injured, told Werntz, of an incident involving a "sparkly cloud."

The workers said they were part way in to a drilling operation when something blew up. An opaque cloud of dust and gas that sparkled like a fireworks display burst from the wellhead, enveloping the men.

Three of those workers were hospitalized with chemical bronchitis and pneumonitis, and two suffered less severe respiratory problems.

The three who were hospitalized developed reactive airway dysfunction syndrome, which Werntz described as "instant onset asthma." It often occurs when people breathe heavily toxic materials.

Symptoms in the three men have persisted for more than two years and two are still unable to return to gas-industry work.

Werntz said the drilling company initially thought the drilling had detonated an underground gas pocket, but eventually decided that a lithium battery in the drilling apparatus underground had exploded, which would better explain the sparkles.

But he noted that the vast majority of injuries to drill-rig workers have been the mundane sorts of falls, fractures, and sprains that occur whenever people work outdoors in high places and with powerful tools.

What's more, he said, all the chemical-related injuries he's seen occurred more than two years ago. Since then, he said, drilling companies have adapted their equipment to the local roads so that their chemical trucks can drive to drilling sites, eliminating the need for hand-mixing.

The Air Up There

Remember we said that about 5.7 million gallons of water and chemicals are needed to drill and frack a well? It all has to be hauled in on trucks. Maybe another 2 million gallons of backflow liquid must be hauled away. Bulldozers have to level about a 100-yard square for the well pad. The heavy drilling equipment, 2,000 yards of well casing, pipes and cables -- all trucked in.

That's a lot of diesel exhaust.

Allen Robinson, PhD, of Carnegie Mellon University in Pittsburgh, presented estimates that nitrogen oxide emissions associated with one well could average about 7 metric tons. Nitrogen oxides are the precursor to ground-level ozone and come from diesel exhaust and from gas flaring, venting, and leakage.

In any given location, 7 tons would not be a major problem. But when thousands of wells are drilled over an area, it can have a substantial impact, he said.

Air pollution is one field in which extensive baseline data do exist, given that nitrogen oxide and particulate levels have been closely monitored since the 1970s.

Robinson showed projections indicating that, by 2020, emissions of nitrogen oxides in the Marcellus region could more than triple over 2009 levels. Smaller but still significant increases in particulates may be expected as well.

These are particularly important in Pittsburgh because the area already regularly exceeds federal limits for ozone in the summer.

That gas drilling can have such impacts has already been shown in western Wyoming, a thinly populated area with heavy shale gas development in the Jonah Basin and little other industry.

Ozone levels well above federal standards have been measured in the Jonah Basin gas fields in winter, apparently because of the combination of nitrogen oxides and sunlight magnified by continuous snow cover.

William Burket, an engineer with the drilling firm EOG Resources, said technical fixes are being applied to reduce the truck traffic at well sites in the Marcellus Shale drilling operations and to refit diesel equipment to be less polluting.

Goldstein said he expects the industry to get cleaner over time because it's in the companies' economic interest. Accidents and spills cost money. And gas that is vented, flared, or lost through defective well casings represents lost revenue.

This is part one of a two-part story. Part two will address mental health effects associated with the drilling boom.

John Gever's spouse works in the University of Pittsburgh's Graduate School of Public Health and helped organize the conference.

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